Method of drawing temper in cutting slots



Patented July 11, 1933 UNITED STATES HUNTINGTON PARK; CALIFORNIA,

PATENT; OiF-FICE CLARENCE J. COBERLY, or LosANGELns, caLrronnra, Assreuon 150mm,- Incl, on i 3 1A coarona'rron or oamronnra METHOD or DRAWING Taurus-m ou'rrirresnors Application filed April 15,

. which to start a slot, preheating the metal surrounding the hole tosuch temperature that combustion of the metal willtake place in the presence of an oxygen jet, directing a cutting jet of oxygen through the hole and moving the oxygen jet so as to cut a slot in the pipe. During the, slotting operation and subsequent thereto cold air is drawn through the slot for the purpose of rapidly cooling the heated walls of the slot in order to harden such walls and thusequip the walls for greater resistance to abrasion by materials carried in the fluids,;which are to subsequently pass.

through the slot.

' ishing'end of the slot than at the starting end thereof, which is an undesirable condis tion especially where alloy steels are employed in the pipes. 7 1 My invention embraces a new and'simple method whereby an isothermal condition will be maintained in the metal" surrounding the slot and will operate to equalize the temper of the slot walls throughout their lengths. The conditions existing inthe present'practice of cutting slots by use of a gas et and a clear understanding of the improvement accomplished therein by the use of my present invention will be made evident 1n the following part of the specification. I

Referring to the drawing, which is for illustrative purposes only,

showing a metal wall, in which a hole has been drilled at which to start a slot andshow ng a cutting torch in position for preheatmg 1930. Serial Nana-"=95.

oxygen jet. r a

Fig. 2 1s a fragmentary planviewcorresponding to Fig. l show'ing the oportionof the metal wall in which a slot is to be cut. I

tion'of the slotting operation. V Fig. 1 1s a plan view corresponding to Fig.

3 showing on the surface of the metal wall preliminary to cutting a slot useof an an isothermal line indicating the thermal con dition of the metal surroundingthe slot.

Flg. 5 1s avlew similar to Fig. lshowing the manner in which the. cutting torchflnaybe employed to correct the unsatisfactory thermal condition of the metal surrounding the slot at the completion of the cutting of the slots by the oxygen jet.

F 1g. 6 is aplan view corresponding to Fig.

5, showing on the surface of. the metal wall the isothermalline existing at the completion of my present slot cutting method. 1

In Figs. 1 and 2,1 show a-metal plate 11 such as thewall of a pipe,,in which slots- I 1 areto be out. To provide a starting point for i It is found that this process, which is fol lowed through in the cutting of a slot, pro duces slot walls which are harder at the fin' the cutting of the slot by use of an oxygen .jet, a small hole12 is drilled through'the plate 11. c'uttingtorch is soplaced that the tip 13 thereof will align with the hole 12 and the metal surrounding the hole 12 is preheated by V theheating'flamesl of the cutting torch tip 7 tobringtlie metal adjacent thehole 12 into cond1t1.on for combustion in the presence of the hole 12 fronrthe cutting torch tip 13 and;

the tip 13 ismoved- ,in rightward direction whereby to cut aslot 16 in'theplate 11. In customary slotting practice when the tip 13 reaches the end of itscut, such as the position indicated at17 in 3, th yg j t v j is cutoff and the tip 13 is removed to a new Fig. 1 is. a vertical partly sectlonedview a position, or the heating flames are discontinued,' the result being that as soon as the slot :is cut by the oxygen. jet no further heat is real cent to the rear end of the slot. It is therefore characteristic of the ordinary method of slot cutting that an unbalanced or unequal-' ized thermal condition exists in the metal of the plate 11 immediately surrounding the slot 16.

Referring to Fig.2, the play of the heating flames 14 on the metal surrounding the hole 12 preliminary to cutting a slotin the plate 11 results in heatfiowing upwardly in the metal surrounding the hole, as indicated by the circular isothermal line 18. During actual cutting by the oxygen jet, the heating flames 14 are moving across the plate 12 so that the amount of heat delivered into or absorbed by the'metal adjacent the slot 16 is .reduced, the result being that the combined heat of the heating flames and the heat generated by the slot cutting operation produces an isothermal line 20 around the completed slot 16, as shownin Fig. 4r,indicating an unfba lanced thermal condition in the metal adjacent opposite ends of the slot 16; In order to harden the walls 21 of the slot 16, air is .drawn through the slot 16 as indicated by arrows 22 in Fig. 3 during and subsequent to the cutting of the slot. The action of the oxygen jet 15 in causing the cutting of metal from the plate 11 to form the slot 16 produces avery high temperature in the surface portions of the slot walls 21 so that these slot .walls are readily hardened in the presence of the air blast which is drawn through the slot, as indicated by arrows 22, especially where the plate 11 is made of alloy steelhaving pronounced hardening characteristics;

As diagrammatically indicated'by the area 23 outlined by the'isothermal line 20 of Fig. 4:, more heat is stored or contained in the metal adjacent the. front end 2 1 of the slot16than in the metal adjacent the rear end 25 of the slot. The heat present in the metal Walls adjacent tothe slot acts to temper the hardened surface portionsof the slot walls 21 so as to relieve possible brittleness thereof,

or to reduce their hardness, this tempering action being in proportion to the amount of heat stored in the metal adjacent the slot 16 and is therefore proportionate to the width of the area 23, which graphically represents the heat stored in the consecutive portions of metal lying along the slot 16. The difference between the thermal condition of the metal adjacent to the front end 24 of the slot 16 andthe metal adj acenttherear end oftheslot 16 results in the slot walls 21 being of a lesser hardness at the front en'd'24t of the slots than at the rear'end 25 thereof, and should a slot cut in the manner previously described be of proper slot wall hardness at the front end 24 of the slot 16, the rear end of the slot will be too hard and possible brittle so as toofii'er poor resistance to abrasion by sand. Conversely to this, should the slot walls'21 be the slot Walls at the front end of the slot would be of insufiicient hardness.

Figs. 1 to 4 show the first part of my invention of a new slotting method and also the slotting method as previously practiced, indicating together therewith the'disadvantages encountered in the previous method of slotting metal plates. My new method is as follows: v,

A hole 12 is drilled in the metal plate 11 andthe flames 14 of the cutting torch tip 13 are directed against the metal surrounding the hole 12 for a sufficient length of time to accomplish the desired preheating thereof. The oxygen valve of the cutting equipment is then opened and a cutting jet 15 is directed through the hole 12 whereupon the tip 13 is moved from itsdotted line position in Fi 3 to its full line position therein, cutting the slot 16 as the result of such movement. At the end" of the slot 16 the oxygen jet 15 is discontinued, but, as indicated in Fig. 5, the torch tip 13 is maintained in position at the end of the slot 16 and the heating flames 14 thereof are caused to play'on the metal adjacent the rear end of the slot for a period oftimesubstantially equal to the time necessary to preheat the metal surrounding the hole'12 preliminaryto turning on the oxygen jet of the torch, the result of this being that an amount of heat is absorbed by the metal adjacent the rear end 25 of the slot 16 to proem a" thermal condition surrounding the slot 16', as indicated by the isothermal line 30 :of The isothermal line 30 outlines an area 31 which graphically indicates the thermal condition existing in the metal adj acent the consecutive portions of the slot 16. This .area 31 is of equal width at itsends, and of but slightly reduced width at its center. Due to ,tlie'balanced heat condition in the metal alongand at the ends of the slot 16, it may be said that by the practice of my new method, an isothermal condition is maintained or'established in the metal of-the plate '11 surrounding the slot 16, and'by tests of the surface hardness of the walls of a slot cut by. my new method it is shown that as the result of such isothermal condition a substantially' constant' hardness is maintained throughout the entirelength of theslot.

. The-practice of my new invention therefore accomplishes the productionof slot walls better adapted; for use in oil well screen or r for strainers, than the slot walls produced by the previous methodof cutting slots by the use of oxygen jets. No strains or'un'equali zed stresses are produced in the metal adjacent opposite ends of the slot and accordingly greatest strength and durability is maintained in the metal wall in which the slots are formed. i V A Iclaim as my invention:

' 1; A method of thecharacte'r described for equalizing thermal conditions in metal surrounding agas-cut slot, consisting of apply-V rounding a gas-cut slot, consisting of applying a flame to the metal adjacent to the rear end of the slot for a suflicient time to produce a. substantially isothermal condition in the metal surrounding the entire slot.

4. A method of the character described for equalizing thermal conditions in metal surrounding a gas-cut slot, consisting of applying a flame to the metal adjacent to the rear end of the slot for a suflicient time after completion of the slot to produce an isothermal condition in the metal surrounding the slot.

5. A method of the character described for equalizing thermal conditions in metal surrounding a gascut slot, consisting of applying heat at a point along said slot and spaced from the front end of the slot after termination of the cutting operation to produce an isothermal condition in the metal surrounding the slot.

6. A method of cutting slots in metal in a manner to produce an isothermal condition in the metal immediately surrounding said slot, comprising: directing a preheating flame to preheat said metal at the starting point of the slot to be made; creating a gas jet to cut said metal at said starting point; moving said jet so as to cut a slot in said metal; and directing a flame against the metal adjacent to the position of the rear end of said slot for a period of time sufficient to produce a substantially isothermal condition in the metal surrounding said slot.

7. A method of the character described forequalizing thermal conditions in metal surrounding a gas-cut slot, consisting of applying heat to the rearward part of the area of metal surrounding the position of said slot described for surrounding the slot.

in addition to the ordinary heat of the slotcutting operation and sufficient in quantity to produce a substantially isothermal condition in the metal surrounding the'slot,

' 8. A method of the character described for equalizing thermal conditions in metal surrounding a gas-cut slot, consisting of applying heat in addition to'the ordinary heat of the slot-cutting operation to the area of metal adjacent a part of said slot following the front end of said slot, so distributed and proportioned in quantity as to produce a substantially isothermal condition 9. A method'of the character described, consisting of: preliminarily heating an area of a piece of metal to raise the temperature to permita burning of the metal; directing a in the metal jet of cutting gas through said metal and A moving same therealong to form a slot; and,

after said'slot-forming operation, heating the 7 metal at the finishing end of said slot to substantially the same amount as the metal at the starting end of said slot Was heated.

,10. A method of cutting a slot in metal by use of a gas-operated cutting torch, said, method including: applying heating jets of saidtorch to said metal to preheat same; di-

recting a cutting jet of said torch through said metal; moving said torch relative to said metal; discontinuing the directing of said cutting jet throughsaid metal; and applying said heating jets to said metal at the finishing end of the slot formed by said cut ting jet, for substantially the same duration as said heating jets Wereapplied at the start 7 ing end of said slot. 11. A method of metal at the finishing end of said slot to produce a substantially isothermal condition in the Walls of said slot.

the character described, consisting of: preliminarily heating an area 7 In testimony whereof, Ihave hereunto set my hand at Los Angeles, California, this 10th day of April, 1930. I

I CLARENCE J. GOBERLY. i 

